Use CodeMirror in /slide #2

Fix title errors in the slide app caused by the present mode

www/slide/inner.html

@@ -72,7 +72,7 @@
         #modal.shown {
             display: block;
             position: fixed;
-            top: 25px;
+            top: 0px;
             left: 0px;
             z-index: 100;
             background-color: black;